This is not an optical illusion, but it takes advantage of exactly the same principles that make optical illusions work: Our eyes and brain don't scan reality like a camera does. Instead, the brain interprets external inputs, building its own reality. No spoilers, just watch.
Vancouver's experimenting with a new speed control creation near École Pauline Johnson Elementary — a painted optical illusion which drivers see as a little girl chasing a ball into traffic. Creepy. We'll call them "Child Bumps." (H/t to Byran!) [DiscoverMagazine]